1. Field of the Invention
The present invention generally relates to arbitration systems. More particularly, the present invention relates to round robin arbitration systems.
2. Related Art
A device or a system has numerous resources. One or more requesters may request to use the numerous resources. Round robin arbitration ensures that the requesters have equal access to the numerous resources. A request bit corresponds to each requester.
Round robin arbitration is a manner of choosing all elements in a list, set, or group equally in some rational order, usually from the top to the bottom of a list and then starting again at the top of the list and so on. In addition, round robin arbitration is characterized by sequential, cyclical allocation of resources to numerous requesters.
Generally, a selection in a round robin arbitration is based on the previous selected request bit and the current request bits seeking access to a particular resource. Moreover, the round robin arbitration outputs an index corresponding to the selected request bit.
In conventional round robin arbiters, the entire round robin arbitration is typically performed with combinational logic in one clock cycle. However, as the clock frequency increases, it becomes difficult to design large bit width round robin arbiters using only combinational logic.
In an effort to overcome the difficulties associated with large scale combinational logic, some designers have divided their round robin arbiter into in multiple stages. In effect, one stage chooses the sub-block which the next stage uses. The second stage tracks the last selection from each sub-block. Unfortunately, this uses many flip-flops and has the added disadvantage that it does not produce results in true round-robin fashion.
In yet another conventional round robin arbiter design approach, true round robin arbitration is performed. However, all variables for each arbitration are re-computed. Thus, in this case arbitration results are produced only once every 2 clock cycles.
Therefore, the typical prior art round robin arbitration schemes are all problematic and suffer different drawbacks.